The present invention relates to a low-pressure discharge lamp having a discharge tube filled with mercury and a noble gas, sealed in a gas-tight manner and provided with electrodes at its ends and having a cap connected to the discharge tube and contact components for connection to a power supply, the discharge tube ends containing the electrodes are arranged adjacent to each other, the electrode-side ends of the discharge tube are fixed--e.g. by means of an adhesive--in the cap, at least a portion of the electrode leads is fixed in the holes of the connecting part of the cap and is connected to conduct electric current, with at least a part of the contact components protruding from the outer side of the connecting part.
The fact that the so-called compact fluorescent lamps are becoming more and more widespread recently is explained by their low specific energy consumption and long life. Nowadays, these low-pressure mercury discharge lamp types are used not only indoors, but their application is continuously gaining ground, e.g. in the advertisement and decorative lighting also--another field where the energy consumed for ensuring the desired lighting effect is an important aspect.
Lamp manufacturers are making efforts to produce fluorescent lamps with continuously increased life and reliability, in the best possible quality and economically.
Several solutions are known for improving the compact fluorescent lamp properties and reducing manufacturing costs. The cap design in the construction of a low-pressure mercury discharge lamp provided with improved cap according to Hungarian Patent No. 196.860 simplifies the insertion of a starter and the connection of current leads connected to the starter. The cylindrical contact components for connection to the lamp-holder are joined with the current leads by means of mechanical fixation as usual in conventional fluorescent lamps. This is performed by pressing a portion of the mantle surface of the contact component from two directions on the current lead inserted into the cylindrical cavity contact component previously mounted in the cap.
The joint produced in this way has several disadvantages. The major one of these is that the joint produced by deforming the corresponding parts is of unsafe quality strongly depending on the physical characteristics of the partner materials of the joint.
A further disadvantage is that the quality of the joint cannot be directly inspected. Due to this, rejects can be separated only in extreme cases when the lamp does not start as early as during manufacturing and joints with intolerable performance from the lamp quality point of view are left in the manufacturing process. Intolerable performance means that, caused by the poor contact between contact component and current lead, the contact resistance in the joint spot may have a wide-range spread adversely affecting electric lamp parameters and quality.
As the shape and dimensions of the lamp parts including the contact component that have to match the lamp-holder are specified by standards, a close control of the location and dimensions of the joint is needed and this increases lamp production expenses.